A diseased or damaged liver, for whatever reason, builds up a back pressure which prevents normal flow of the venous blood through the portal vein to the liver so that deterioration of the liver is aggravated in proportion to the dearth of blood supplied to it. Normally, a liver tends to rebuild itself if supplied with a sufficient amount of venous blood and, in the past, it has been suggested to supplement the flow of venous blood to the liver by mechanical devices, for example, a pump to force flow of venous blood to the liver at a pressure to overcome the resistance of the liver to receipt of the venous blood at normal pressure. No practical way of accomplishing this has been devised since such treatment, to be effective, must be continuous and any treatment involving a pump would necessarily have to be administered by qualified persons under controlled conditions at periodic intervals such as in a hospital. It is the purpose of this invention to provide a method and device for continuously supplementing the flow pressure of venous blood to the liver which may be contained entirely internally of the patient so as to require no participation on his part or supplementary assistance.